Prime mover control system



Dec. 31, 1940. .1. RING ETAL 2,227,417

PRIME MOVER CONTROL SYSTEM Filed. April 25, 1938 l llt Il,

Patented Dec. 31, 1940 2,227,417

UNITED STATES PATENT OFFICE` PRIME MOVER CONTROL SYSTEM Joseph J. Ring and Beverly R. Nichols, Wauwatosa, Wis., assignors to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corpo- Y ration of Delaware Application April 25, 1938. Serial No. 203,986

27 Claims. (Cl. 253-143) This invention relates generally to prime mover It is therefore an object of the present invencontrol systems 4and particularly to systems contion to provide a control system for a prime mover i trolling a prime mover ofthe type having adjustin which system the rate of movement oi the able runner vanes. gate controlling the flow of operating fluid to o A control system for a prime mover should be the prime mover follows a predetermined plan 5 accurately and quickly responsive to any condiregardless of the operation of other portions of tion tending to cause a change in the prime mover the system tending to cause the gate to move at speed. Response to such speed changes should, a different rate. however, follow a predetermined rate dependent Another object of the invention is to provide l on the characteristics of the machine being gova prime mover control system in which the gate 10 erned. Thus it is frequently desirable to open controlling the flow of operating fluid to the the operating fluid control gate slowly and interprime mover is opened during starting to a premittently or to provide for a different rate of determined position corresponding substantially speed movement under different conditions. The to normal speed at no load and is subsequently l degree to which the gate is opened under diipermitted to open farther under the control of l5 ferent conditions should also be controllable to a speed governor. limit the power output or the load on the ma- Another object of the invention is to provide chine. Load or power limitation is normally ema prime mover control system which will secure ployed during both the starting and the normal stable predetermined operation of the prime movoperation of the machine to avoid excessive gate er at all loads from no load to full load and will opening which would hinder initial synchronizaallow only a predetermined speed droop to take tion of the governed machine, with other maplace `over the entire load variations. chines or which would allow the governed ma- Another object of the invention is to provide a chine to tend to supply an excessive portion of prime mover control system which will interrupt 'the total load. If an excessive load is taken by operation of the prime mover upon the occurrence 25 one machine, the machine will operate outside of abnormal prime mover operating condition or its normal range and will be unstable. To secure upon the failure of the control system itself. adequate and stable regulation of a machine Another object of the invention is to provide subject to varying load, the control system must a control system for prime mover generating 0 be provided with means by which a predeterunits in which fluid pressure supplying the oper- 30 mined speed drop or droop is permitted when the ating cylinders in the control system is either load on the unit changes. manually or automatically interrupted to cause Modern machines are frequently to be operated a shutdown of the prime mover followed by cloat remote points and without the constant supersure of a blocking valve to prevent redistribution vision of an attendant in the station itself. It is of operating uid to the control system. 35 accordingly necessary to provide a governing sys- Another object of the invention is to provide tern with means by which abnormal operating a control system for a prime mover having adconditions or failure of the governing mechanism justable runner vanes in which the runner vanes itself will operate to shut down the machine. are automatically caused to assume steep angular io When such shutdown occurs, it is desirable that position prior to starting of the prime mover to 40 the usual supply of oil pressure to the control increase the starting torque thereof and are autosystem is interrupted to make the control sysmatically returned to normal position after the tem ineffective until the entire control system starting operation is completed. has aga-in been placed in the proper operating Objects and advantages other thanthose above condition. When the prime mover governed is a set forth will be apparent from the following de- 45 turbine with adjustable runner vanes, it is very scription when read in connection with the acnecessary to adjust the vanes to a steep angle companying drawing in which; to obtain the maximum torque during starting Fig. 1 diagrammatically illustrates a hydraulic and to make such adjustment automatically. 'I'he turbine driven generator unit having applied 7'" cont.ol system should therefore provide for setthereto an automatic speed control system em- 50 ting the runner vanes to a steep angle prior to bodying the various elements of the present instarting and such setting should be relinquished vention and, to the normal vane control mechanism at least Fig. 2 diagrammatically illustrates, in side view, as soon as the machine is at its full load operatthe-structure of the runner vane control portion 5f' ing speed. of the control system, which is particularly adapt- 65 ed for adjustment to produce steep tilt position of the runner vanes upon starting.

The various elements constituting the control or governing system are not shown in their relative positions, their true size nor in their relative proportions but are shown diagrammatically to more clearly facilitate explanation of the construction and operation of the system.

Referring to the drawing by characters of reference, the control system is shown as applied to a prime move such' as a hydraulic turbine designated at I and shown as being of the adjustable propeller type driving an alternating current generator II connectible with and disconnectible from the usual power line by conventional switch gear means well known in the art and therefore not shown. The turbine I0 comprises a casing I2 which forms a peripheral water inlet in which are mounted a series of movable vanes forming a gate I3. The term gate is intended to include means other than those disclosed and which may be used for the purpose of controlling and guiding the flow of pressure fluid to any prime mover to which a governing system embodying any of the elements herein shown, is applied. The gate vanes are mounted on stems I4 journaled at the top and bottom in portions of the casing I2. The upper stem portions extend through the upper portion of the casing to provide for attachment of a. conventional linkage connection with a shifting ring I6 which is adapted to be shifted into different positions and to control the position of the gate vanes and hence to control the flow of fluid to the turbine. The shifting ring I6 is connected with and actuated by the piston I1 of a fluid pressure operated servomotor I8.

The turbine I0 is connected with generator II by a hollow shaft I9 which is supported against movement at angles to its axis by a bearing 2| and on which is mounted the turbine runner comprising a hub I from which extend, substantially radially, a series of vanes 22 journaled in suitable bearings in the hub. The inner ends of the vanes 22 are severally provided with trunnions 23 and are connected by linkage mechanisms 24 with a cross head 26 which is guided to be reciprocated axially of the shaft by an operating rod 21. It will be understood that the relative positions of the runner vanes govern the area of the fluid fiow passages or openings between the vanes and that adjustment of the runner vanes increases or decreases the area of the flow passages depending upon the direction of the movement of the vanes. The cross head 26 is fixed to the lower end of the operating rod 21 which extends upwardly through the runner shaft I9 and is fixed to the piston 2B of a fluid pressure operated servomotor 29 which is mounted in or is formed as a portion of the runner shaft preferably adjacent to the point where the runner shaft is joined to the hollow generator shaft 3|. 'I'he servomotor piston 28 is double acting and two tubes 32 and 33 are arranged in telescopic relation within the generator shaft for the purpose of supplying fluid pressure to the two sides of the piston to operate the same in either direction. 'I'he outer tube 32 supplies fluid for the downward movement of the piston 28 and connects with the lower chamber of a distributing head 34 secured to the top of the generator frame. -The tube 32 extends downwardly through the hollow bore of the generator shaft 3| and is sealed against the escape of fluid pressure therefrom. The inner tube 33 supplies fluid pressure for the upward movement of the piston 28 and is fixed thereto and rotates with the shaft 3|,

'I'he tube 33 communicates with an inclined passage 36 through the piston 28 and is provided with perforated openings 31 in the tube portion extending into the upper chamber 38 of the distributing head 34.

Pressure to the runner servomotor 29 is controlled by a pilot valve 39 which is governed by a pilot valve operating mechanism which includes an extension 4I from the piston I1 of the gate operating servomotor I8 to which extension is fastened a rod 42. The rod 42 is connected with one arm of a pivotally mounted bell crank 43 having a crank 44 flxedly mounted on the spindle of the bell crank. A rod 46 is connected with the crank 44 and, through a crank 41, rotates a shaft 48 on which is mounted a cam 49. The cam 49 engages a roller 5I adjustably mounted on a lever 52 which is pivotally mounted at one end at fixed point 53 and is downwardly biased at the other end by a spring 54 connecting the end of the lever with a fixed point in the control system. 'I'he lever 52 is connected by a. link 56 with one end of a oating lever 51 to which is connected the stem of the pilot valve 39. Movement of the gate servomotor piston I1 transmits movement through leverage 4I, 42, 43, 44 and 46 to the shaft 48 and the cam 49 from which movement is transmitted through the second leverage including elements 5I, 52, 56 and 51 by which the pilot valve 39 is moved to admit fluid pressure from a pipe 58 through pipes 59 or 6I into the pressure head 34 and from which pressure head fluid is discharged through the pipes 59 orY 6I through a discharge pipe 62. 'Ihe cam 49 provides means for readily producing a topographical surface by which a definite relation may be obtained between the setting of the gate I3 and the positioning of the runner vanes 22. The cam is preferably made of laminated material to facilitate formation of the proper topographical surface thereof after tests have been made with the entire unit in operation in its final setting. The cam 49 is splined on the shaft 48 to permit movement along the axis thereof and its position may be adjusted by a fork 63 engaging the cam 49 and mounted on a screw 64 rotatable by a hand wheel 66 to change the position of the cam and hence to vary the contour lines of the topographical surface of the cam which may come in contact with the roller 5I. 'I'he position of the cam 49 is indicated by a suitable gear toothed connection between the hand wheel 66 and a rotatably mounted disk 61 marked with suitable subdivisions and provided with a non-rotatable pointer 68.

When the gate opening is small and the runner vanes are in a comparatively flat position, the starting torque of an adjustable propeller type turbine is very low. A relatively long period of time is therefore required to bring the turbine up to the speed at which the unit may be connected to the transmission line. Further, with the runner vanes in a relatively flat position, the gate must be opened a relatively large amount to overcome the starting friction of the prime mover unit. It is then necessary to move the gate quickly in a closing direction to prevent overspeeding of the turbine after rotation has begun. Means are therefore provided by which the runner vanes may automatically be initially set in a comparatively steep position and then returned to the desired operating angle. Such means include an arm 1I loosely mounted on the cam shaft 48 in such position as to permit engagement of a roller 12 mounted on the arm, with the lever 52 to thereby operate the valve 39,

The position of the arm 1| is determined by adjustable arms 13 and 14 which are mounted to rotate with thecam shaft 48.

Means must also be provided by which the pilot valve 39 is restored to the `neutral or midposition after each operation of the valve in either direction. The restoring movement is derived from the inner shaft tube 33- which moves with the runner vane servomotor piston 28. The upper endof the tube 33 is connected through rod 16, bell crank 11, link 18, bell crank 19 and link 8| with one end of the floating lever 51 to which the stem of valve 39 is connected. The bell crank 19 is provided with a suitable gear toothed connection with arotatable indicating dial 82 cooperating with a suitable pointer 83 to indicate the angular displacement of the runner vanes. The arc of the dial 82, between the runner vane flat position and the runner vane steepest angular position, is divided into ten equal divisions to provide readings in tenths, which is customary when referring to runner vane positions.

To start the turbine, the arm 1| and roller 12 mounted thereon, are manually brought into vertical position thereby .lifting lever 52 which moves the stern of pilot valve 39 upwardly and admits fluid pressure to the underside of the servomotor piston 28 thereby tilting the runner varies 22 into a steep angular position. As the gates open, the arm 1| is automatically rotated in a counterclockwise direction, due to gate opening action on rod 46, until the arm 1| is forced out of engagement with lever 52 thus permitting the roller 5| to engage the cam 49 `which then maintains a predetermined relation between the degreeof gate opening and the runner vane setting. Whenever the gates are moved toward the closing position, the arm 13 and the arm 1| are rotated in a clockwise direction which results in lifting of the lever 52. The runner vanes are therefore again set in a steep angular position which permits the turbine to be again started under the most favorable conditions.

The interconnection of large power generating systems in which momentary load fluctuations are relatively small and occur over a relatively large period of time, as compared with the total load, necessitates governing means of extreme sensitivity capable of instant response to the slightest speed variations to maintain adequate distribution system stability and the proper frequency regulation in the distribution system. Such means are herein shown as comprising a unit including an electric motor connected with and therefore responsive to the frequency (or speed), variations of the prime mover generator unit. The electric motor drives a set of flyballs controlling a servomotor for imparting motion to a Afloating lever controlling a pilot valve which regulates the flow of fluid pressure to the gate operating servomotor |8. The flyball head herein illustrated is already known and will therefore be described only sufficiently to allow com prehension of its functional cooperation with other portions of the control system herein disclosed. The motor 86 is mounted on a housing 81 and drives a set of flyballs 88 arranged within the housing. As is known, the position of the flyballs 88 varies dependent on the motor speed and such variation of position provides movement of a control valve regulating the admission of fluid pressure to and the discharge of fluid pressure from a servomotor, the servomotor and its control valve being only generally shown and designated B9. The pressure supply pipe and the pressure discharge pipe for the servomotor 89 are indicated at 9| and 92. Theilyball servomotor acts on a floating lever 93 pivotally connected with a main lever 94. One end of the main lever 94 is pivotally connected with a collar 96 which is resiliently mounted by a spring 91 abutting against a nut 98 on the stem of a pilot valve 99 for regulating the iiow of fluid pressure and from the gate operating servomotor Il. Pressure is applied to the valve 99 from a suitable source through the pipe 58 and is discharged from the valve through the pipe |02. The pipe connections between the valve and the opposite sides of the servomotor piston |1 are designated by |03 and |04. Any change in the conditions of the line which results in a change of the speed of the motor 86 is immediately translated into movement of the ilyballs 88 which act on the servomotor 89 and hence on the levers 93 and 94 to move pilot valve 99. The gate operating servomotor |8 therefore immediately commences to vary the opening of the gate I3 to correct the flow of fluid to the prime mover |0 dependent on the degree and the sense of the speed change.

Movement of the gate servomotor I8 must, however, be interrupted before the effect of decreasing or increasing speed of the prime mover |0 would be apparent in thedistributlon line and hence would produce change in` speed of motor 86, to thereby prevent successive over or under regulation or so-called hunting of the unit. Valve 99 must therefore be returned to its neutral or midposition with a time delay after the initial operation thereof. Such compensating or restoring means includes the servomotor piston rod extension 4| and the rod 42 connected with one arm of the bell crank 43. The other arm of the bell ycrank 43 is connected with a rod |06 connected with one end of a lever |01, the other end of which is connected with a pivot |08 on which are mounted a bell crank |09 and a crank Intermediate the endsof lever |01 is connected one piston ||2 of a dashpot ||3 having a second piston ||4 connected with one end of the main lever 94. The dashpot l I3 also includes adjustable valves ||6 and ||1, spring biased in closed direction, which open automatically upon I movement of the pistons ||2 and ||4 and which, when the spring bias is overcome, allow'fiow of pressure from one chamber to the other of the dashpot and an adjustable needle valve ||8 which allows a predetermined quantity of fluid ow between the chambers of the dashpot. The action of lever 94 is stabilized by a spring ||9 mounted between the dashpot piston ||4 and a boss on the cover of the dashpot and by a spring |2| mounted between the cover of the dashpot and a portion of a synchronizing means.

The synchronizing means is well known in the art and will therefore be only briefly described. Such synchronizer is, however, necessary to a complete control system and is accordingly included herein to permit a complete description of the operation of the system. The synchron'izer includes a nut |22 bearing a gear or gear teeth and engaging with the thread of the screw threaded rcd of the dashpot piston ||4. The nut adjusts the degree of compression of spring |2| and accordingly determines the action and posi tion of the piston ||4. The gear teeth of nut |22 engage with an elongated gear |28 rotatably mounted to be driven by gears |24 operable either CFI manually or remotely by hand wheel or motor |26.

If the yball head, due to a decrease in the prime mover speed, lowers the floating lever 93. the main lever 94 and the collar 96 are lowered to depress the piston of valve 99 which results in movement of the servomotor piston I1 toward the right to open the gate I3.

The motion of the servomotor piston |1 moves leverage 4|, 42, 43, |06 and |01 and forces the dashpot piston ||2 upwardly which produces a partial vacuum and pulls the piston ||4 down against the action of the compression spring |2|. The valve ||1 is opened until the spring 2| restores the dashpot piston I I4 to its balanced or midposition. The downward movement of the piston ||4 lowers the right hand end of lever 94 and causes the opposite lever end together with the collar 96 to rise to a higher position which restores the pilot valve 99 to the neutral position. If the load change is small or gradual, the movement of the piston ||2 will be correspondingly slow and may not cause movement of the dashpot piston ||4 because the needle valve ||8 permits iiow of small quantities of fluid from one chamber of the dashpot to the other chamber thereof. However, if the load change is sudden or large, a sudden or large displacement of the piston ||2 occurs and the bypass valve I|1 is opened to pass fluid between the dashpot chambers which valve ||1 thus controls the rate of return to the balanced position of the piston ||4. When the displacement of the piston ||4 is comparatively large, the leverage and the pilot valve 99 are quickly returned to the midposition. The flyballs in the meantime have adjusted themselves to the new load condition and lever 93 has been returned to the normal governor operating position. A speed increase reverses the above action which causes compression under the dashpot pistons I|2 and I |4. Valve ||6 is then opened to bypass uid and the ow through the needle valve ||8 is reversed.

Even if the restoring means for the gate servomotor valve were absolutely perfectly designed and manufactured, a governing system provided with such perfect means would only tend to keep the speed of the governed unit constant regardless of the load thereon. Due to the inherent qualities of different units; at the same speeds, some units will tend to take all of the load and others will tend to run without load. When a plurality of machines of different characteristics are supplying power to the same distribution line, it is necessary that the speed of the machines be allowed to droop an adjustable predetermined amount at various loads to maintain stable operation of the machines. The control system is therefore provided with means for limiting or varying the effect of the restoring mechanism above described. Such limiting means comprise one arm of the bell crank |09 which is connected with a rod I3| which is in turn connected with a bell crank |32 having one arm thereof slotted. 'I'he slotted arm of the bell crank |32 is connected by a rod |33 with one end of the lever 93. Upon the occurrence of a change, in the distribution line which causes movement of the control system, the restoring limit device shifts the position of levers 93 and 94 and tends to keep the valve 99 open or closed for an adjustably greater length of time than would otherwise occur thus allowing the unit speed to vary by a predetermined amount necessary to keep the unit under a predetermined load at the given speed.

Shown immediately adjacent the restoring limit device is a device for indicating the position of the vanes comprising the gate I3. Such indicating device includes a rack |36 mounted on the arm and held by a spring |31 in engagement with a gear on the pivot of a pointer |38 operating over a dial |39. Operation of the gate servomotor and of the leverage of the valve restoring means connected with the servomotor actuates the arm and rotates the pointer |38 over the dial to give a constant indication of the gate position.

The conditions of the load supplied or of the distribution system itself or the characteristics of the unit being governed frequently require that the rate at which the unit is governed, that is, the rate at which operating iiuid is admitted to the prime mover is made variable to meet the conditions existing. In the case of an adjustable runner vane turbine as herein disclosed, it is of course necessary that the rate of movement of both the gate and of the runner vane be made variable. Such rate control mechanism includes a crank |4| mounted on the pivot |08 which is rotated by the restoring mechanism. The end of crank |4| is connected with a rod |42 which is connected with the end of a crank |43 mounted on a pivot |44 on which is mounted a plate |45 bearing a ange |46 formed with cam surfaces. The cam |46 is engaged between pins on one end of an arm |41 rocking about a pivot |48. The other end of the rocker arm |41 is made forked to engage a collar |49 mounted on the stem of valve 99. Movement of the valve 99 in either the opening or closing directions is thus limited by the engagement of collar |49 with the rocker arm |41 and the engagement of the rocker arm pins with cam |46 which cam is rotated by the movement of the restoring mechanism. Naturally, the contours of cam |46 will be made to secure limitation of the rate of movement, either during or at the end of its stroke, of the valve 99 as desired dependent on the characteristics of the unit or of the distribution line.

It is desirable at times to limit theload or the power output of the turbine or to operate the turbine with the gate so blocked that it cannot be moved beyond predetermined limits. Such load limit device should be adjustable to any desired degree and at any time. The load limit includes a crank mounted to rotate with pivot 44 and connected with a rod |52. The rod |52 is connected with one end of a lever |53 having a swivel nut |54 as its fulcrum which is adjustable manually or remotely by means of the hand wheel or motor |56. The other end of the lever |53 is connected with a rod |51 having a spring joint |58 and the rod |51 is connected with one arm of a three armed bell crank |59. Another arm of the bell crank |59 extends into the path of movement of the collar 96 on the stem of the pilot valve 99. An opening movement of the gate I3 rocks the bell crank lever |58 in a clockwise direction and thereby raises the stem of valve 99 to move the gate towards closing position. At the same time the restoring mechanism will return the valve 89 to midposition and further movement of the gate is stopped. That gate may also be closed regardless of the position of the floating lever 94 and to any desirable extent by rotation of the threaded spindle urging the fulcrum nut |54 to a lower position and resulting in an upward movement of the bell crank |59 which raises the valve 66 through the overtravel spring |58. Movement of the load limit is transmitted to a lever |6| pivotally mounted at |62. The lever |6| has connected with one end thereof, a rack s |63 held by a spring |64 in engagement with a gear onthe pivot of a pointer |66 moving over a dial |61. The setting and momentary position of i:the load limit device are thus constantly indica ed.

Means must be provided to prevent opening of the gate |3 during starting beyond the position corresponding to synchronous speedl o! the unit, until the flyball or governor head has reached the speed at which it will govern the unit. The third arm of the bell crank |68 ls connected with a link |68 adjustably engaging withthe slotted end of a link |68 connected with the lever 63 at the point of connection thereof with the piston rod of the flyball servomotor 88.

Upon starting the unit, the right hand end of the main lever 64 is raised, thereby lowering the pilot valve 66 and opening the turbine gate I3. The flyballs are still at rest and the link |66 is at its lowest position allowing the link |68 to be at v its lowest position andengage the notch in a latch block |1|. As the gate moves toward open position, the cam plate |46 rotates in a counterclockwise direction and acts on the bell crank |56 by way of the leverage including members |5|, |52, |53, |51 and |58 and raises levers 83 and 84 to restore valve 66 to midposition to stop the movement of the turbine gate at some predetermined opening, such as that required for the turbine to reach synchronous speed. As soon as the flyballs start to rotate and come to nearly synchronous speed, the stop link |68 is lifted out of the path oi the latch block |1| and the collar 66 and levers 64 and 83 may drop which permits the gate to be opened to a fuller extent as determined by the fiyballs.

The operation of aprime mover generating unit, particularly when such operation is not constantly supervised, requires the provision of means by which the entire unit may be shut down upon the occurrence of abnormal operating conditions of any portion of the unit. Such shutdown mechanlsmshould operate fully automatically not only to close the turbine gate but should also shut off the uid pressure from the various duid pressure operated devices of the control system upon the occurrence of such conditions as a hot bearing, the opening of a circuit breaker or the like. Control system operating fluid pressure is supplied to .the entire control system through the pipe |12 from the usual source of substantially constant pressure. To perform the iirst o! the above two functions, pressure is taken from the pipe |12 through the pipe |13 to a valve |14 which is operated by a solenoid |16 energizable o in the usual manner from the portions of the unit subject to abnormal operation. Valve |14 is connected to the pressure supply pipes |11, |16 and |16 connecting with ball valves |8I. |82 and an operating cylinder |63 having its piston under spring pressure. Pressure passing through the ball valve |8| may iiow through the pipe |84 to an operating cylinder |86 with its piston under spring pressure opposing the fluid pressure supplied thereto. The piston rod of the 7o cylinder |86 is formed with an adjustable lost motion connection |61 to engage a bell crank |88 having one arm extending into the path of movement of the collar 66 on the stem of the pilot valve 68.

The control system is also provided with locking means requiring the cooperative action of the above mentioned valves |8|, |82 and the cylinder |83 and with a latch comprising a double armed crank |6| engaging the stems serving to open the ball valves |6|, |82 and mounted on a pivot |62. `The pivot also has mounted thereon a latch |63 connected at one end with the piston of the cylinder |83 and provided at the other end thereof with a roller |84 normally in contact with a rollertrack |86 and a stop |61, both the roller track and the stop being mounted on the extension 4| from the gate servomotor piston rod. The control system is also provided with a manually operable latch and operating means particularly for the purpose of operating the unit when the automatic governor is to be dismantled for inspection or repair. A cross head |68 is mounted at the connection between the gate servomotor extension 4| and the pushrod 42 of the restoring mechanism. The cross head is formed with a square aperture therethrough to adiustably receive the squared end of a threaded rod |88 running in a sta tionary nut 26| rotatable by a hand wheel 262 through suitable gearing.

-The second of the above mentioned functions of the automatic shutdown device, namely the function of shutting ofi the supply of uid pressure to the pressure operated cylinders of the control system, is performed by the solenoid valve |14, ball valves |`6| and |32 and latch cylinder |83 in combination with a shutoff valve comprising a valve casing 266 provided with a passageway therethrough which may be closed ofi by an inclined diiierential piston 261 housed in a cylinder in the valve casing. The lower end of the cylinder is closed by a cover plate providing a cylinder for a hydraulically operated control valve comprising a differential piston 2|| joined by a stem of decreased cross section, with a second piston 2|2 which controls the drainage from below the piston 261 through a passage 2I6. A small portion of the seat oi the differential piston 2|| is subjected to the pressure in pipe |12 through the passage 2|4 to facilitate opening of the valve 2|2 whenever the ball valve |82 is open to provide communication between the pipe |12 and the under side of the piston 261 through the passages 2 I4 and 2|8. The valve 261 is then hydraulically balanced and is moved to closed position by the action of the compression spring 268. Drainage from the valve 2|| takes place through the pipe 2|3, ball valve |82, pipe |18 and solenoid valve |14.

Briefly stated, the operation of the automatic shutdown and the latch cooperating therewith is as follows. If the turbine is shut down and is to be started, the latch engages stop |81 to hold gates I3 closed, energization of the solenoid |16 opens valve |14 admitting iiuid pressure to the interlocking ball check valves |8| and |82 and to the latch operating cylinder |83. Ball check valve |82 ,is opened and pressure is admitted under the piston 2|| to raise the control valve 2|2 and cause the shutoff piston 261 to admit oil to the valve 66 which is then in the position for gate closing and causes servomotor |6 to tend to close the gate I8 thus relieving the action of the stop |61 against latch |65. After relief of the gate opening tendency on the stop |91, fluid pressure admitted to the latch operating cylinder |83 forces its piston and rod upwardly and moves the pivotally mounted latch arm |63 in a counterclockwise direction to move the latch |66 downwardly away irom the stop member |91 carried by theextension 4|. The stem of valve |8| now forces 'the ball check downward and oi its seat to admit oil under the piston of the shutdown cylinder |86. 'I'he shutdown piston is therefore forced upwardly and rotates the bell crank |88 clockwise to allow the valve 99 to move toward the gate opening position. `The gate I3 opens until stopped by the power limit mechanism. As soon yas the yballs 88 come up tospeed, the link |68 is drawn out of latch block |1| 'and the prime mover is then fully under the control of the governing system. If the circuit of the solenoid |16 should be vinterrupted by a temperature relay or by any other protective means or by the shutdown switch, the valve |14 will close the pressure supply pipes to the valves |8| and |82 and to the latch cylinder |83 and will open the drain connections. The compression spring of the shutdown cylinder |86 then forces the oil under the piston out through the'ball valve |8| to the drain, and raises the bell crank |88 which moves the pilot valve 99 vto a position at which the gate servomotor |8 closes the gate |3. During the above operation the piston of the latch operating cylinder |83 is forced downwardly by the compression spring causing clockwise rotation of the latch |95 and lever |93, |94 until the roller |94 engages track |96. The track moves toward the left upon movement ,of the servomotor toward gate closed position and the roller |94 leaves the track so that the latch cylinder may pull the latch |95 into its latching position. The trip lever |9| is rocked together with the latch |95 in a clockwise direction and opens the ball valve |82 to allow pressure to flow from under the piston 2|| of the control valve 2|2 to the drain through the pipe 2| 3, ball valve |82, pipe |18, and solenoid valve |14. AA small portion of the seat of piston 2|| is exposed to the pressure in pipe |12 through the passageway 2|4 and the piston 2|| is forced downwardly until the valve 2|2 closes the drain from below the shutoff valve piston 2|1. Pressure is now admitted from the iluid pressure supply pipe |12 through the passageway 2|4 and 2|6 to the under side of the shutoff valve piston 201 thereby balancing the pressure acting on the valve whereupon the spring 208 closes the valve to prevent iow of fluid pressureto any of the operating cylinders of the system. It will thus be observed that as long as the roller |94 engages, the track |96 the shutoff valve 201 remains open until the operation of closing of gate is completed, which is as long as the roller |94 engages the track |95 and that only then can the final latching close the shutoi valve. It will also be noted that the stem of valve |8| moves upwardly thus allowing the ball check to seat and preventing pressure through solenoid valve |14 from entering shutdown cylinder |86 until latch |95 has been released even though the solenoid |16 is energized.

The essential elements of the system are shown in the positions of the normal operation of the prime mover but the sequence of the operations of the system will now be described from starting of the prime mover generating unitl from standstill, that is, with the gate in closed and latched position, the runner vanes set for a steep angular position to obtain increased starting torque of the turbine and with the automatic shutoi valve closed; through normal operation of the unit and to the rlnal stopping of the unit.

The solenoid |16 is connected with a source ball check valve-'|82 is opened and of current supply by a conventional switch not shown.l Closure of said switch energizes the solenoid |16 and opens the control valve |14. Fluid pressure from the supply pipe |12 is therefore admitted to the interlocking check valves |8|, |82 and to the latch operating cylinder |83. The ball check valve |8| remains closed but the fluid pressure ilows under piston 2|| of the control valve 2|2 for the shutoi valve 201. Closure of the valve 2|2 then enables the pressure in the supply pipe |12 to open the automaticshutoi valve 201 and pipe |12 can then supply the full pressure to the several regulating cylinders in the control system. As stated above, the gate I3 is already closed while the turbine is at rest. However the water pressure acting on the gate has a tendency to open the gate by an amount equal to the lost motion in the gate mechanism which tends to force the stop |91 against the latch |95. To overcome the friction between the stop |91 and latch |95 and to unlatch the gate operating mechanism, the pilot valve 99 is caused to move slightly upwardly so that the servomotor piston takes up the lost motion in the gate closing direction. The necessary movement of the pilot valve 99 is obtained by manually controlled movement of the synchronizer operating means |26 or the load limit operating means |56.

The synchronizer, which may be actuated by the hand wheel or -by a remotely controlled motor |26, is now operated to raise the one end of main lever 94 which depresses the collar 96 and the pilot valve 99 connected therewith. The pilot valve is now held open and iluid pressure passes to the left face of the piston |1 of the servomotor |8 to open the ga'te |3 and set the prime mover into operation. As soon as the servomotor piston |1 moves toward the right, the dashpot ||3 is actuated Ito restore the lever 94 and the collar 96 to the neutral position. The rod |42 produces a counterclockwise rocking movement of the cam plate |46 until the stop block |1| engages the link |68 connected with the bell crank |59 and thereby blocks further opening movement of the pilot valve 99 beyond the opening determined by the setting of the block |1|. The rate limit cam |46 engages the pins on rocker arm |41 and limits the rate of opening movement of the pilot valve 99 to prevent the servomotor piston I1 from advancing too rapidly. Adjustments of the synchronizer are repeated until the speed of the lyballs closely approaches the full load normal speed operation of the prime mover. At such approximately normal speed, the governor head assumes the automatic control of the prime mover by raising orlowering lever 93 as may be required 4to secure synchronous operation of the unit. The fulcrum point of the oating lever 94 is then at the point of connection thereof with the daslipot ||3. As soon as the flyballs closely approach a normal speed, thelink 68 is pulled away from the latch block |1'| thereby permitting the rate limit device to function over its entire range.

To obtain the maximum starting torque, the runner vanes are set for a steep angular position, tha-t is, arm 1| and roller 12 are brought into a vertical position. The lever 52 and roller are then raised to necessary steep position and hold the pilot valve 39 in position to admit pressure to the lower face of piston 28 which operates rod 21 and cross head 26 to rotate the runner vanes 22 into the steep angular position necessary to start the runner rotating. As

the gate operating servomotor piston I1 moves toward the right which is the gate opening position, the servomotor motion is transmitted through the extension 4|, rod 42 and crank 43 .to rod 46 which rotates cam shaft 48 to move the stop 14 in a counterclo'ckwise direction until it pushes the roller 12 out of engagement with the lever 52 thus allowing the roller 5| to again engage the cam 49. The cam thereafter determines the position .of valve 39 thus securing` positioning of the runner vanes in a predetermined relation to the gate opening to secure the most favorable operating conditions for the turbine.

During normal operation of the unit, load and frequency changes in the distribution line immediately affect the speed of the motor 86 and the position of flyballs 99. The servomotor 89 accordingly shifts the lever 93 which raises or lowers the gate pilot valve 99 to operate the gate servomotor I8. Movement of the gate servomotor actuates the 'restoring leverage 4|, 42* 43, |96, |01

and the dashpot ||3 which shifts lever 94 and re-` turns the pilot valve 99 to neutral position to interrupt the gate movement. Movement of the cam 49 from the restoring leverage provides for movement of the runner pilot valve 39 to control the runner servomotor 29 and the leverage- 16--Bl restoring the runner valve toneutral position. Minor speed variations are controlled exclusively by the iiyball head without action of the dashpot due to the regulated ow of iiuid from one dashpot chamber to the other through the needle valve IIB. Larger speed changes bring into play the internal action of the dashpot which thus attempts to limi-t quick movement `of the gate servomotor to a short interval of time. Large and quick fiyball and dashpot movements are, however, spread over a relatively long period of time by the operation of the rate limiting cam |49 and its rocker arm |41 acting on the stem of pilot valve 99. The power output or load limit performs its well known function of l preventing opening of the gate beyond a predetermined point to limit the power obtainable from anyone unit provided with such power limiting means. The safety connection between the load or power limit device and the flyball head actsto prevent full opening of Ithe gate during starting operation and thus automaticallylimlts the unit speed during starting or if the flyballs are not operating.

The operation of the unit is normally interrupted either by operation of the synchronizer IRL-|26 in the reverse direction lfrom that above mentioned for starting at which time the synchronizer will pull down the lever 94 and will raise the valve 99 to cause a closing of gate I3; or the load limit device |5||59 may be operated by turning either the hand wheel or by operating the motor |55 in a direction to lower the nut |54 which lowers -lever |53 and raises the arm of bell crank |59, to press against the collar 96 and thus to raise the stem of the valve 99 to close the gate I3. Another method of stopping the unit is to `deenergiae solenoid |16 which then operates the automatic shutdown device as above described. Emergency operation of the shutdown device ha-s already been previously described and accordingly is not repeated.

Consideration of the 'above disclosure will show that the control system herein set forth provides for the control of a prime mover having a gate controlling the ilow of operating fluid to the prime mover and in which the gate is operated by a fluid pressure operated servamotor. The gate servomotor is controlled by a speed responstoring mechanism to erating 'within its most stable range regardlessV sive means herein called a Ilyball or governor head and provided with a servomotor operating a pilot valve controlling the pressure now to the gate operating servomotor. Means comprising a leverage and a `dashpot are connected between the gate operating servomotor and the fiyball head to restore the pilot valve to its neutral position. In addition to the above elements essential in any control system, the present system is provided with means for controlling or limiting the rate of gate operation which means include Ithe 'cam plate and rocker arm connected with the restoring mechanism and with the gate pilot valve, Mea-ns are also provided for limiting the power output of the prime mover both during nor-mal operation of the control system and particularly when the prime mover is being started, that is, when the fiyballs are ineffective, and includes an adjustable leverage operated from the restoring mechanism on the gate pilot valve and another adjustable leverage connecting the first mentioned leverage with the iiyball head. A speed droop control device connects the levers actuated by the ilyball head with the rekeep the prime mover opof the power output which may be required therefrom.` Shutdown and shutoi means are provided to stop the prime mover upon the occurrence of abnormal conditions and .also to render the control system inelective. The several valves and power operating cylinders cooperating to form shutdown and shutoff devices may be operated either in response to abnormal condition or voluntarily as may be desired.

When the prime mover is asturbine with adjustable runner vanes as herein disclosed, in addition to the above elements which were stated to be essential to any 'control system, it is necessary that a servomotor be provided to adjust such vanes and, when a duid pressure operated servo,-

motor is used, a pilot valve is required. A definite relation must be maintained between the gate and the runner vane settings and such relation is obtained by a leverage actuated by a cam which is rocked by a connection with the gate operating servomotor. Such adjustable runner machine Ashould be provided with means to initially set the runner vanes at a steep angle to improve the prime mover starting characteristics and such means are provided in an arm acting on the pilot valve actuating leverage and with operating and limiting stops also operated from the gate servomotor.

Although but one embodiment of the present invention has been illustrated and described herein, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit oi the invention or from the scope of the appenged claims.

It is claimed Patent:

l. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for Ycontrolling said gate operating means, means for restoring said gate operating means to midposition, and meansactuated by said restoring means for controlling the rate of movement oi said gate operating means.

2. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means. lor operating the gate, means reand desired to secure by Letters auY storing said gate operating means to midposition,

a cam plate actuated by said restoring means, and

- a rocker arm engaging said gate operating means and the cam surface of said plate for controlling the rate of movement of said gate operating means.

3. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, a servomotor for operating said gate, a flyball governor responsive to the speed of the prime mover for controlling the operation of said servomotor, a leverage connected with said servomotor, a dashpot connecting said governor with said leverage, said leverage and said dashpot cooperating to restore said servomotor to the midposition thereof. a cam plate actuated by said restoring means, and a rocker arm engaging said gate operating means and the cam surface of said plate for controlling the rate of movement of said gate operating means. l

4. In a control system for a prime mover having a gate controlling the iiow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means. means for restoring said gate operating means to midposition, and means for limiting the degree of action of said restoring means on said `gate operating means to control the speed droop of the prime mover.

5. In a control system for a prime mover having a gate controlling the ow of operating uid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for .restoring said gate operating means to midposition, and an adjustable leverage connecting said gate operating means with said restoring means for limiting the action of said restoring means on said gate operating means to control the speed droopofthe prime mover.

`16'2 In a'control system for a prime mover having a gate controlling the flow of operating fluid thereto. a servomotor for operating said gate, a fiyball governor responsive to the speed of the prime mover for controlling the operation of said servomotor, a leverage connected with said servomotor, a dashpot connecting said governor with said leverage, said leverage and said dashpot cooperating to restore said servomotor to the midposition thereof, a cam plate actuated by said restoring means, a rocker arm engaging said gate operating means and the cam surface of said plate for controlling the rate of movement of said gate operating means, and an adjustable leverage connecting said gate operating means with said restoring means for limiting the action 60 of said restoring means on said gate operating means.

7. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the midposition thereof, and an adjustable leverage connecting said gate operating means with said gate restoring means for limiting the power output of the prime mover during operation thereof.

8. In a control system for a prime mover having a gate controlling the flow of operating fluid u thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the midposition thereof, means for limiting the power output of the prime mover during operation thereof, and means for eliminating the action of said power limiting means during starting of -the prime mover.

9. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid position thereof, means f or limiting the power output of the prime mover during operation thereof, and an adjustable leverage connecting said speed responsive means with said power limiting means for eliminating the effect of the latter during starting of the prime mover.

10. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid position thereof, a source of iluid pressure, a cylinder having a piston engageable with said gate operating means, and valves controlling pressure flow to and from said cylinder upon the occurrence of predetermined conditions of operation of the prime mover to supersede all other means in controlling operation thereof.

1l.. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for Acontrolling said gate operating means, means for restoring said gate operating means to the mid position thereof, means for automatically interrupting operation of the prime mover upon the occurrence of predetermined conditions thereof, and means controlled by said interrupting means for interrupting the supply of energy to the entire control system.

12. In a control system for a prime mover having a gate controlling the flow of operating uid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid position thereof, a source of fluid pressure, a cylinder having a piston engageable with said gate operating means, valves controlling pressure iiow to and from said cylinder upon the occurrence of predetermined conditions of operation of the prime mover to supersede all other means in controlling operation thereof, and a latch cooperating with said valves to control the pressure now to said cylinder.

13. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid position thereof, means for automatically interrupting operation of the prime mover upon the occurrence of predetermined conditions thereof, and a valve controlled by said interrupting means for rendering the entire control system ineffective upon operation of said valve.

14. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto and having a runner with adjustable vanes, `:mea-ns for operating said gate responsive to the speed of the prime mover, means for adjusting the position o! said runner vanes responsive to the operation of said gate operating means, and means operable by said vane adjusting` means for setting the runner vanes at a steep angle prior to starting of the prime mover.

l5. In a control system for a prime mover having agate controlling the iiow of operating fluid thereto and having a runner with adjustable vanes, means for operating said gate responsive to the speed of the prime mover, a servomotor for adjusting the position of the runner vanes, means controlled by said gate operating means for controlling the operation of said servomotor, and means operable by said gate operating means to adjust said servomotor controlling means to set the runner vanes at a steep angle prior to starting of the prime mover.

16. In a control system for .a prime mover havlng a gate controlling the flow of operating iiuid thereto and having a runner with adjustable vanes, means for operating said gate responsive to the speed of the prime mover, la servomotor for adjusting the -posltion of the runner vanes, means for controlling the operation of said servomotor, a leverage controlled by said gate operating means for operating said servomotor controlling means, and an arm operated by said gate operating means and acting on said leverage to adjust the same to set the runner vanes at a steep angle prior to starting of the prime mover.

17. In a control system for a vprime mover having a gate controlling the ow of operating fluid thereto and having a runner with adjustable vanes, means for operating said gate responsive to the speed of the'prime mover, a fluid pressure operated servomotor for adjusting the position of the runner vanes, a valve controlling the flow of fluid pressure to and from said servomotor, a leverage controlled by said gate operating means for controlling movement of said valve, an arm movable into engagement with said leverage to 'cause movement thereof to set the runner vanes at a steep angle prior to 4starting of the prime mover, and means operable by said gate operating means to move and to limit the movement of said arm.

1B. In a control system for a prime mover having a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operated means, means for restoring said gate operating means to mid position, a leverage connected with said restoring means, a plate having a cam surface and being mounted for oscillation by said leverage, and a pivotally mounted rocker arm engaging said gate operating means and the cam surface of said plate for controlling the rate of movement of said gate operating means.

19. In a control system for a prime mover having a gate controlling the iiow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling the said gate operating means, means for restoring said gate operating means to the midposition thereof, a cylinder having a piston engageable with said gate operating means, a valve interrupting the flow of pressure to said cylinder upon the occurrence of abnormal conditions in the operation of the prime mover, and a valve allowing discharge of fluid under pressure from said cylinder upon operation of the iirst said valve.

20. In a control system for a prime mover hav-n ing a gate controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling the said gate operating means, means Ior restoring said gate operating means to the mid position thereof, a cylinder having a piston engageable with said gate operating means to cause movement thereof in gate closing direction and compressing a spring upon the admission of fluid pressure thereto, a solenoid valve closed upon the occurrence of abnormal operation of the prime mover, and a valve opened by expansion of the spring in said cylinder upon closing of said solenoid valve, said valves respectively controlling the admission to and the discharge of fluid pres sure from said cylinder.

21. In a control system for a prime mover hav-n ing a gate controlling the ow of operating iiuid thereto, means for operating the gate, means rem sponsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid position thereof, means for automatically interrupting operation of the prime mover upon the occurrence of predetermined conditions thereof, a latch engageable with said gate operating means, and pressure operated means for actuating said latch.

22. In a control system for a prime mover hav-n ing a gate controlling the flow of operating fluid thereto, means for operating the gate, means re sponsive to the speed of the prime mover for con-n trolling said gate operating means, means for re storing said gate operating means to the mid po-In sition thereof, means for automatically interrupt-i ing operation of the prime mover upon the occurrence of predetermined conditions thereof, a latch engageable with said gate operating means, a iluid pressure servomotor for actuating said latch, and a valve operated responsive to abnora mal operation of the prime mover for interrupta ing supply of pressure to said servomotor.

23, In a control system for a prime mover hav ing a gate controlling the flow of operating fluid thereto, a fluid pressure operated servomotor for operating the gate, a fluid pressure operated valve for controlling the supply of pressure to said servomotor, and a plurality of separate valves opm erable responsive to different conditions to cause a closing of said pressure operated valve upon the asA occurrence of abnormal operation of the printemover.

24. In a control system for a prime move:T having a gate 'controlling the flow of operating fluid thereto, means for operating the gate, means responsive to the speed controlling said gate operating means, means for restoring said gate operating means to the midMV position thereof, a leverage connecting said speed responsive means and said gate restoring means for limiting the power output ofthe prime mover during operation thereof, an adjustable leverage of the prime mover for connecting said speed responsive means with said power limiting leverage, and a stop actuated by said restoring means to limit the movement of said adjustable leverage in one direction to thereby eliminate the eii'ect of said power limiting leverage during starting of the prime mover.

25. In a fluid pressure operated control system for a prime mover having a gate controlling the flow of operating iiuid thereto, means for operatlng the gate, means responsive to the speed of the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid-position thereof, valve means for interrupting the operation of the prime mover, valve means for shutting oi the riow of fluid pressure to the entire control system, and automatic means responsive to the occurrence of predetermined abnormal conditions to cause operation of both said interrupting means and said shut off means.

26. In a fluid pressure operated control system for a prime mover having a gate controlling the flow of operating uid thereto, means for operating the gate, means responsive to the speed of the prime mover for controlling said gate operat- -ing means, means for restoring said gate operating means to the mid-position thereof, valve means for interrupting the operation of the prime mover, a fluid pressure operated valve for shutting off the ow of fluid pressure to the entire control system, and a plurality of valves automatically responsive to the occurrence of predetermined abnormal conditions to cause operation oi both said interrupting means and of said shut o1! valve.

27. In a uid pressure operated control system for a prime mover having a gate controlling the ow of operating fluid thereto, means for operating the gate, means responsive to the speed o1' the prime mover for controlling said gate operating means, means for restoring said gate operating means to the mid-position thereof, a iluid pressure operated valve for shutting of! the ow of fluid pressure to the entire control system, a valve automatically responsive to predetermined abnormal conditions to cause operation thereof, and a plurality of valves controlled by said automatic valve, all of said valves cooperating to cause operation of both said interrupting means and said shut off valve.

JOSEPH J. RING. BEVERLY R. NICHOLS. 

